Of if is concaveup on one side of and concave down on the other side.
点，如果在点的一侧是凹的，而在的另一侧是凸的。
2
The studio estimates its Concave Roof system could help the school collect up to 28 cubic metres of rainwater, which would contribute to its running.
工作室估计该凹屋顶系统可以为学校收集高达28立方米的雨水，这将有助于学校的运行。
3
Firstly, a telescope system is made up with a concave lens and a long-focus convex lens, by which the angle of the parallel beam from the collimator can be change.